1. Field of the Invention
This invention relates to a roller-guided feeding device for enabling a workpiece to move on a worktable of a woodworking machine along a feeding route, more particularly to a roller-guided feeding device with a servo valve assembly disposed to control the air flow of a stroke pneumatic operating unit for facilitating feeding of a workpiece along a feeding route.
2. Description of the Related Art
A conventional roller-guided feeding device includes a guiding unit mounted on a worktable and having a plurality of guiding rollers, a feeding unit having an arm which is pivoted relative to the guiding unit, and a feed-in roller which is rotatably mounted on one end of the arm, a pneumatic operating unit including a directional control valve which is shifted between closed and open positions by virtue of an air pressure from an air pressure source, a pneumatic cylinder and a piston rod which are disposed downstream of the control valve and which are connected to the end of the arm, and a manually operated actuator. When the actuator is operated to shift the control valve to the open position, the piston rod is moved by the air pressure to turn the end of the arm closer to the guiding rollers so as to feed a workpiece forward along a feeding route defined by the guiding rollers and the feed-in roller while holding the workpiece in place.
However, during the feeding operation, the user needs to operate the actuator with one hand or foot so as to maintain the control valve in the open position, which is inconvenient. Moreover, after a part of the workpiece is cut, the actuator has to be released to return the control valve to the closed position so as to permit outward turning of the arm for subsequent cutting of the remaining part of the workpiece, which is also inconvenient.